Watch Online Free FlixHQ. When World War II broke out and the Japanese army occupied the northeast, they repeatedly sent mysterious troops into a massive cave near Dida Juzi. According to legend, the Japanese discovered an immense treasure there. Sixty-five years later, a Japanese tycoon travels to Er Long Lake to invest in building a factory, only to unexpectedly awaken a water monster. Suddenly, Er Long Lake becomes the center of nationwide attention, sparking a series of hilarious events revolving around the creature.